Answer:
Dry and rough skin is troublesome for many people.  The main cause of dry skin is the seasonal change in temperature and humidity.  In order to protect our hands, we should start by understanding the structure of our hand skin.
 
Let’s take a close look at our hands.  The superficial lipid layer of our hands has a waterproofing function which essentially prevents water from evaporating from the body. Also, ceramide, a complex lipid in the epidermis layer, increases this prevention.  Thus, lipids are crucial to maintain healthy skin.
 
Lipids can melt with hot water or detergents as easily as dietary oil, therefore, dry skin is a common problem for many housewives because of their daily routines such as washing dishes. Also, we see more dry skin in winter than in summer, because the amount of lipid is proportional to the temperature. Moreover, an interesting hypothesis describes that the secretion of lipids is related to male hormones; therefore, females are more likely to have dry hands.

Protection and care for dry skin is mainly achieved by using moisturizers or creams.  Application after every washing is recommended because then it is easy for the moisturizer to be absorbed by the skin.  This treatment forms a veil on the skin and prevents water loss. For those with relatively severe skin damage, moisturizer can be applied and covered by plastic wrap over night.

As well as external treatment, some nutrients, for example, Vitamins A and B₁, are said to be helpful to keep our skin healthy.  Carrots and eels are rich in Vitamin A; Vitamin B₁ is found in peanuts and pork.


Acknowledgement
We thank Higashiyama clinic for his careful teaching and kind support for this answer.
 
 

This article is translated by Chemistryquestion.com from the original article in Chemistryquestion.jp.  Please let us know if you find any errors.

(C.H)